Z7 auto ISO seems seriously flawed

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j2scriba New Member • Posts: 6
Z7 auto ISO seems seriously flawed
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The auto ISO setting has two adjustable parameters:
"minimum shutter speed" and "maximum sensitivity"
One would expect the algorithm to select ISO as low as possible to achieve the mimimum shutter speed in automatic modes and increase ISO if light is too low to do that, until the maximum sensitivity is reached.

However, this is not quite what is happening.
If maximum ISO is reached, the A-mode increases shutter speed regardless of the mimim shutter speed. At first I thought there was some hidden option I had overlooked, but Nikon support (Germany) confirmed that this is how it's supposed to work. The reasoning behind it was explained like this: "Since A, S, P are automatic modes, the camera does whatever it takes to achieve good exposure."

This may be an acceptable design paradigm for a point-and-shoot, but for a presumably professional target group this seems bizarre. For me, this feature is useless in this implementation. Here's the scenario I'm looking at: I need to shoot from a moving car and need a minimum shutter speed of 1/250s. I want to shoot wide open to get windscreen dirt out of focus so I select A-mode at open aperture. The camera adjusts shutter speeds shorter than 1/250s. When things get dark, e.g. in tunnels, ISO is increased. When the scene gets really dark and there's not much to see, there's no point in turning ISO all the way up to max and blow out whatever light patches there might be to reveal only noisy shadows, so I set a max ISO of, say 8000. With the strange auto-ISO design the camera will disregard minimum shutter speed and motion-blurred pictures.

As everybody knows, ISO is mostly irrelevant in digital cameras (after hitting a camera-specific optimum ISO) and post processing RAW files to boost shadows will produce very similar or better results to high ISO during exposure, as we have better control over noise and much better preserved highlights. So headline-grabbing extreme-ISO shouldn't be used for serious work, anyway.

The strange disregard for minimum shutter speed pretty much spoils this feature. Underexposure can be fixed in post, blurred pictures cannot. Am I the only one who thinks that "No" (as in "No longer exposure than I specified") should really mean "No" in this setting?

Nikon Z7
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